Tracer



June 10, 1958 G. E. RYCKMANl TRACER 3 'Sheets-Sheet 1 Filed May 4. 19553 Sheets-Sheet 2 D u gu/amd H1.: Hrwueys June 10, 1958 G. E. RYCKMANTRACER Filed May 4, 1955 June 10, 1958 G. E. RYcKMAN 2,838,268

vTRACER Filed May 4, 1955 s sheets-sheet s @L-fr l m fi g M WM Q l Q R.N 3

1N V EN TOR. asr l@ cx mu BY ,6M Mya-JM TRASER George E. Ryckman, EastLiverpool, Ohio Application May 4, 1955, Serial No. 505,890

i s creams. et 251-3) This invention relates to tracers that are usedfor followingtemplates and other patterns in metal working machines,such as lathes, milling machines, shapers and planers.

It is among the objects of this invention to provide a tracer which issimple in construction and operation, which requires only a very slightpressure to operate it, which is strong and durable, which can be usedwith either fully automatic or manually controlled machines, and whichwill protect from injury any uid pressure indicator that is connectedwith it.

In accordance with this invention, the tracer head is provided with aninwardly extending cylindrical recess that has an annular shoulderfacing the inner end of the recess. The head also is provided with a uidpassage having an outer end adapted to receive fluid under pressure froma line connected with a gauge. The inner end of the passage terminatesin a central orifice at the inner end of the recess. A barrel isdisposed in the recess, from which it projects, and has an enlargedinner end normally pressed against the shoulder by a spring. Theperiphery of the barrels enlarged end is spherical and slidably engagesthe encircling Wall of the recess. The portion of the barrel between itsenlarged end and the outer end of the recess is spaced from the wall ofthe recess so that the barrel can be rocked in the head. The inner endof the barrel is provided with iluid ports connecting the portions ofthe recess at opposite sides of the enlarged end of the barrel. Carriedby the inner end of the barrel is a valve member that normally is spacedaxially of the recess from the iluid orilice. Projecting from the outerend of the barrel is a stylus that is adapted to be swung laterally,such as by a template or a surface being gauged, to tilt the barrel inthe head. When the barrel is tilted, the valve member will be movedcloser to the orifice to restrict ow of uid therefrom. Preferably, thevalve member is formed from a plunger slidably mounted in an axial borein the inner end of the barrel. A spring normally holds the plungerprojected from the barrel a predetermined distance so that furthertilting of the barrel after the plunger engages the head beside theorifice will cause the plunger to be pushed into the barrel.

The preferred embodiment of the invention is illustrated intheaccompanying drawings, in which Fig. 1 is a side view of my tracermounted on the outer end of an arm attached to a lathe `or the like;

Fig. 2 is a View of the dial of the uid pressure indi cator that ismounted in the arm;

Fig. 3 is an enlarged vertical section through the tracer;

Fig. 4 is a fragmentary section showing the stylus de ilected a standardamount;

Fig. 5 is a similar view showing the stylus deected the maximum amount;and

Fig. 6 is a graph showing the relation between indicator reading andstylus deflection.

Referring to Fig. l ofthe drawings, the tracer T is mounted in a socket1 projecting from'the bottom of a 2,838,263 Patented June 10, 1958 theslide. The boss is held against the inner lend of the p micrometer byacoil spring 12 encircling a rod 13 that is slidably mounted in the endof the block. By turning the micrometer, the slide can be moved alongthe block to obtain tine adjustments for the position of the tracer. Atemplate of the profile to be duplicated is mounted securely on themachine frame within reach of arm 8, and

the relationship between tracer and template is perfected by themicrometer.

Arm 8 has a hollow downwardly-extending portion, the lower end of whichis formed for adjustable connection yto the tool slide 15 of a metalcutting machine, such as a lathe, for example, in such a way as topermit normal motion of the tool slide. Disposed in an opening in theupper part of the hollow portion of the arm is a iluid pressureindicator 16, the inlet of which is connected with apassage 17 thatbranches out opposite sides of a block 18 secured to the arm. One branchis connected by, a conduit 19 with a source of iluid under pressure,such as compressed air, and the other branch is connected by a flexiblehose 20 with the tracer T. Flow of air from the irst branch into therest of the passage is controlled by a needle valve 21. As is customarywith apparatus of this kind, the compressed air flows through the tracerand out to the atmosphere, but its flow through the tracer is restrictedso that back pressure is created which registers on the indicator. Anydeviation of the indicator needle from a predetermined point willindicate a` change in the ow restriction at the tracer.

As shown in Fig,- 3, the tracer head, which is held in slotted socket 1by a set screw 22, includes an inverted cup-like housing 23 providedwith a cylindrical recess 24 that extends upward from its lower end. Thehousing above the recess is provided with a threaded axial bore throughit `concentric with the recess and containing a plug 25 that,preferably, projects down into the recess. The downwardly projectingportion of the plug forms the central portion of the wall of the upperor inner end of the recess. The lower end of the plug is provided with acentral oritice 26 that opens into an axial passage 27,.

the upper end of which opens laterally into a radial nipple 28 extendingthrough a vertical slot in the side of the socket. The nipple isconnected to the flexible hose 20 leading to indicator 16. By turningthe housing on the plug, the orice at the lower end of the plug can beadjusted vertically in recess 24. The desired adjustment is maintainedby a set screw 29 in the housing, bearing against the plug. Another setscrew 31 holds a bushing 32 in the enlarged lower end of the recess.lThe internal diameter of the bushing is a little less than the diameterof the recess above it, so that the bushing forms supporting means inthe form of an annular shoulder 33 (Figs. 4 and 5) in the recess facingits inner or upper end. All of the elements 23 to 33 make up the tracerhead.

Loosely mounted in the recess is a barrel 36, which has.

an enlarged upper end that normally rests on shoulder 33 a shortdistance below orifice 26. Although this end may rest against theshoulder by gravity and the uid pressure above it, it is preferred topress the barrel down against the shoulder by means of a light coilspring 37 encircling the lower end of plug 25 and compressed between thebarrel and the upper end of the recess.V The portion of the barrel thatextends down through the bushing to the Vlower or outer end of recess 24has a smaller diameter than the inside of the bushing so that there isan annularv assess space 38 between them that will permit the barrel tobe tilted or rocked in the head. As provision must be made for escape offluid from the head, the barrel preferably is provided with severalcircumferentially spaced fluid ports 39 extending down through itsenlarged upper end and opening into space 38 so that fluid issuing fromorifice 26 can flow out of the lower end of the head. To keep the barrelcentered in the recess at all times, the periphery 4l) (Figs. 4 and 5)of its large upper end spherical and.

slidably engages the wall of the recess. The two, therefore, remain incontact even when the barrel is tilted.

The barrel is provided with an axial bore 42 through it, in the upperend of which a plunger 43 is slidably mounted. The plunger has anenlarged lower end that normally is pressed up against a shoulder 44(Fig. 5) by means of a light coil spring 45 compressed between thebottom or inner end of the plunger anda cross pin 46 extending throughthe center of the barrel. The pin is held in place by a sleeve 47encircling the barrel, on which it is held by a set screw 48 threaded inthe sleeve and extending through a hole in the side of the barrel. Theupper end of the plunger normally projects a short distance from thebarrel and serves as a valve member 49 spaced a predetermined distancefrom orifice 26 directly above it. This distance depends upon thevertical position of the plug 25 in the head, and, as pointed outbefore, is adjustable.

In the lower end of barrel bore 42 a vertically adjustable stylus 51 ismounted. It is held in place by means of sleeve set screw 48. The sideof the lower endof the stylus is adapted to engage a template 52 or thelike, indicated n broken lines, and normally to be deflected or pushedlaterally by the template a predetermined or standard amount such as,for example, .O20 inch.

Before the tracer is pressed against a template or the like, the stylusextends straight down from the head as shown in Figs. 1 and 3, becausethe upper end of barrel 36 rests flat against shoulder 33. This is thezero deflection position of the stylus, in which the resistance to flowof compressed air through the tracer will cause the indicator needle tomove to the set position on the dial shown in Fig. 2. As the stylus isdeflected' from zero position, the barrel will be tilted in the tracerhead and will move the valve member 49 at the upper end of the plungercloser to orifice 26, as shown in Fig. 4. will restrict the orificestill more, so the back pressure will rise and the indicator needle willapproach the on size position. When that position is reached, theoperator will know that the work is being cut correctly. Any

greater or lesser deflection of the stylus, caused by improper tracingof the template, will be shown immediately on the indicator by movementof its needle one way or the other from the on size position, becausethe air passage through the tracer will be closed or opened more.

As the stylus deflection increases, the upper end of the plunger valve`43wvill approach closer to plug 25 until they touch at one side oforifice 26. However, the stylus can be deflected still further in orderto reduce the likelihood of the stylus being bent or the templatedamaged,

because the barrel 36 can move up around the plunger s that is stoppedby plug 2S. On the other hand7 this further tilting of the barrel andplunger will not close the orifice still more, which might damage theindicator by exposing it to too much air pressure. To the contrary, thepoint at which maximum closing of the orifice occurs is when the plungerfirst touches the plug, and further deflection of the stylus as thebarrel slides up on the plunger serves only to swing the upper endsurface of the plunger down away from the orifice and thereby allowsincreasing air flow through the orifice. This is a very desirablefeature because it prevents the back pressure on the indicator frombecoming excessive and ruining it. Fig. 5 shows the tracer in maximumdeflection position, with the side of the barrel engaging the lower endof bushing 32. A

This

The relation between stylus deflection and indicator reading is showngraphically in Fig. 6, which is practically self-explanatory. lt will beseen on the graph that the tool will be on size when the stylus isdeflected .020 inch, and that before the indicator needle can run offthe scale because of over deflection of the stylus, the valve in thetracer will start to open wider and the needle will fall back toward setposition. This reversal 'of needle movement will start to occur when thestylus deflection reaches .O35 inch in the example illustrated. Ofcourse, this is a situation that the operator should do his best toavoid, by holding the indicator needle at on size position on the dial.Nevertheless, if he does run over too far, the indicator will beprotected from damaging back pressure in the manner described in thepreceding paragraph.

Since during normal operation of this tracer the only part that is movedby the template o1' other surface being traced or gauged is thebarrel-stylus unit, and since the movement is only a slight tiltingresisted by a very light spring, the pressure required to deflect thestylus is so small that the templates can be made of very lightmaterial, such as heavy paper. In spite of this, the tracer is sturdy,inexpensive and simple in construction.

According to the provisions of the patent statutes, I have explained theprinciple of my invention and have illustrated and described what I newconsider to represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

I claim:

l. A tracer comprising a head provided with an inwardly extendingcylindrical recess having supporting means facing the inner end of therecess, the head also being provided with a fluid passage having anouter end adapted to receive fluid under pressure and having its innerend terminating in a central orifice at said inner end of the recess,said orifice being positioned to direct fluid from said passage towardthe outer end of the recess, a tiltable barrel in the recess andprojecting therefrom and having an enlarged inner end normally seated onsaid supporting means, the periphery of said enlarged end beingspherical and slidably engaging the encircling wall of the recess, theportion of the barrel between its enlarged end and the outer end of therecess being spaced from the encircling wall of the recess, the tracerbeing provided with fluid outlet ports leading out from the recess, avalve member carried by the inner end of the barrel and tiltabletherewith and normally spaced axially of the recess from said orifice,and a stylus projecting from the outer end `of the barrel and adapted tobe swung laterally to tilt the barrel and valve member in said head,whereby the valve member will be moved closer to the orifice to restrictflow of said pressure iluid therefrom.

2. A tracer according to claim l, in which said head includes a housingcontaining said recess and having an axial bore extending into the innerend of said recess, and a plug mounted in said bore and adjustableaxially thereof, the plug containing said fluid passage and orifice.

3. A tracer according to claim l, in which the inner end of the barrelis provided with said fluid outlet ports connecting the portions of saidrecess at opposite sides of said enlarged end of the barrel.

4. A tracer comprising a head provided with an inwardly extendingcylindrical recess having supporting means facing the inner end of therecess, the head also being provided with a fluid passage having anouter end adapted to receive fluid under pressure and having its innerend terminating in a central orifice at said inner end of the recess,tiltable barrel in the recess and proiecting therefrom and having anenlarged inner end normally seated on said supporting means, theperiphery of said enlarged end being spherical and slidably engaging theencircling wall of the recess, the portion of the barrel between itsenlarged end and the outer end of the recess being spaced from theencircling wall of the recess, the tracer being provided with uid outletports leading out from the recess, the inner end portion of the barrelbeing provided with an axial bere, a plunger slidably mounted in saidbore, a spring normally holding the plunger projected from the barrel apredetermined distance, and a stylus projecting from the outer end ofthe barrel and adapted to be swung laterally to tilt the barrel andplunger in said head, whereby after the barrel is tilted in the head farenough for the plunger to engage the head beside said orifice, furthertilting of the barrel will cause the plunger to be pushed into saidbore.

5. A tracer comprising a head provided with an inwardly extendingcylindrical recess having an annular shoulder facing the inner end ofthe recess, the head also being provided with a iluid passage having anouter end adapted to receive fluid under pressure and having its innerend terminating in a central orice at said inner end of the recess, atiltable barrel in the recess and projecting therefrom and having anenlarged inner end normally seated on said shoulder, the periphery ofsaid enlarged end being spherical and slidably engaging the encirclingwall of the recess, the portion of the barrel between its enlarged endand the outer end of the recess being spaced from the encircling wall ofthe recess, the inner end of the barrel being provided with fluid portsconnecting the portions of the recess at opposite sides of said enlargedend, the barrel being provided with an axial bore therethrough, aplunger slidably mounted in the inner K end portion of said bore andprojecting therefrom, a pin extending across the central portion of thebore, a coil spring in the bore compressed between the pin and the innerend of the plunger, means limiting the distance the plunger can be movedaway from the pin, and a stylus projecting from the outer end of saidbore and axially adjustable therein, the outer end of the stylus beingadapted to be swung laterally to tilt the barrel and plunger in saidhead.

6. A tracer comprising a head provided with a iluid passage having anoutlet, a plunger spaced a short distance from said outlet in the pathof uid issuing therefrom, a tiltable barrel provided with an axial boreslidably receiving the plunger, means supporting the barrel for tiltingmovement, a spring normally holding the plunger projected from thebarrel a predetermined distance, and a stylus projecting from the outerend of the barrel and adapted to be swung laterally to tilt the barreland plunger, whereby the plunger will be moved closer to said outlet torestrict flow of pressure uid therefrom.

References Cited in the file of this patent UNITED STATESVPATENTS1,124,471 Leidecker `Jan. 12, 1915 1,959,178' Sassen May 15, 19341,997,890 Wall Apr. 16, 1935 2,283,296 Temple May 19, 1942 2,397,494Kuppersmith Apr. 2, 1946 2,675,652 Chiappulini Apr. 20, 1954

